well im kinda concerned on my engine temp..me and my wife spent a weekend on our beautiful maxum 2400scr...well the boat plans beautifully..cruises at around 3800rpm and temp gauge is just under 175...however sometimes with the same revs the temp is just above the 175 mark...i then lower the revs to around 3400K and get back to 3800K and temp is at a steady 175..if i rev her up to 4000K, temp starts creeping up very very slowly..mechanic told me to keep her at 4000revs to see whether the alarm goes off however im concerned of doing any damage..new thermo..risers..manifolds..however no luck..all hoses ok and no leeks...compression very good on all cylinders..could there be some water restriction somewhere else? mechanic did some checks by removing hoses to see the amount of water coming out and he says that all looks good....engine 5.7 V8 carb thunderbolt ignition.

Any advice on some other checks i can do myself without any more mechanic bills?!

impeller changed as well..however i was told that a bad impeller will overheat the engine even at idle..last saturday had eight people on board and engine ran at 2200rpm (obviously not on a plane) for around 30mins and temp gauge on 160 all the time :?

engine symptoms with 2 adults and full tank of gas and water...
cruising at 3600 - 175
cruising at 3800 - 175
cruising at 4000 - just above 175 however it starts climbing really really slowly that is when i get down to 3800 again and temp is at a steady 175

It would have to get real hot to do any harm Clint and it's not unusual at all for temp to climb a bit when the engine is under more load. You don't mention how hot it's gotten though.

Run it. It will likely creep to 180, 185. If it approaches 190 you might want to look into it. My 2400 SC3 with 350 MAG and B3 runs consistantly right around 175 and creeps to maybe 180 when working hard. Remember though, there are differences between temp senders and gauges - calibration wise. The only way to really know the true temp is to shoot various hoses and engine parts with a thermo gun and compare that to the gauge.

what they said....the other place to look is in the heat exchanger..make sure that there are no blockages going on there....may need a coat hanger straighened out to push thru the tubes to make sure they ar eclear...but other than that..sounds pretty normal...

SP irate:

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gaz - temp on gauge when at 4K rpms is in the middle of the 175 mark and the next mark which i thnk would be around 190. nevertheless alarm does not sound but i will let it run on 4K longer next time im out and see what happens..i will let u know on the outcome..

no...freshwater cooled only...so if you don't have FWC system...then about the only thing that can cause the engine to get hot at WOT is a bad pump ....or ....blocked passages and hoses...or ......bad thermostat....

SP irate:

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SP - The water pressure coming out of the engine is good..i disconnected the hose coming from the engine into the thermostat and started the engine. At idle the water pressure seemed ok to me...would that elimiate a faulty water pump or is there another check i can do? thermostat..manifolds..risers have all been changed...could there be a restriction when the water exists the risers?

another quick perhaps silly question..im checking all the fluids..engine manual states that there is the engine oil..power stearing oil..outdrive gear oil and transmission oil..can anyone tell me where i can find the transmission oil on a V8 5.7lt Carb ?

the only oil you need to check is the engine oil.....pwr steering.....and drive oil ...the drive oil is in the bottle at the top of the engine...stinky green oil....can't miss it...

as for water pressure...I think your good to go unless the alarm kicks in.....so...relax some...enjoy the boat..

SP :mrgreen:

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Don't compare your life to others. You have no idea what their journey is all about.
------------------------
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2008 Bayliner 340 - "Wild Whim"
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I live in my own little world....but it's okay-they know me here!!!

thanks for clarifying the oil issue SP..I checked them out and only the power steering needed some topping..

with regards to the overheating issue, today i kept the boat at 4K rpms and temp was at 175 climbing up very very slowly as usual..i then tilted the motor up and the temp was climbing up fast until it reached the mark after the 175-i reckon that would be around 190-200..alarm didnt sound however i couldnt risk it..what could cause the engine to overheat when i tilt the engine upwards? could the outdrive block the intake pipe?

it really depends on how high you raised the drive.....water comes in from the 8-10 holes on the side of the leg.....water not getting a clear shot at those holes will reduce pressure causing the pump to not be able to draw the water in well enough....temps may rise at that point....but if the alarm didn't go off..then your still operating within the proper range....look...a street car will normally run between 180 and 210 degs....a boat engine will run between 160 and 190 degs...if your in that range...then everything is ok.......about the only thing that can cause an engine to over heat....is;
1)bad thermostat..should be about a 160 deg stat in the engine
2)blown head gasket
3)holes in the drive blocked by a bag or something
4)bad raw water pump impeller
5)exhaust manifold or risers
6)blocked water passages..
7)low oil levels in the engine

it sounds like you've had all of those checked out......

I've run my engines at 4k rpm for hrs on end...they never over heated...they did increase in heat since your generating more heat at that rpm....

SP :|

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
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I live in my own little world....but it's okay-they know me here!!!

thanks for the reply..i tiltled the drive to a point that lower drive was still completely immersed in water..mechanic is clueless..he asked me to check the water hose from the transom plate to the engine..he is thinking tilting the engine upwards is blocking the hose pipe..i'll keep you posted tomorrow with any news..however all other causes you have mentionned i have gone through and even replaced thermo risers manifolds..compression very good on all cyclinders, no blockage in intake holes..clueless... :|

spoke to mech today..we will be connecting another gauge set to the engine to check the accuracy of the current gauges..if problem persits we will use an infrared temperature reader to read the engine temperature on various parts of the cooling system..

Hi Clint
Just another thing, you may want to check the distributor, if the advance system is not operating (may be seized up or something ) them you motor will be running to far retarded at the higher R.P.M. and this will also rase the temperature

I have a 2002 2400scr and my temp are the same as yours 175 is normal and wot 4400rpm it will rise 10 deg .I have changed the raw water impeller cleaned the tubes it seems to be normal for the 2400 scr I have had no problems you should be ok good luck.

Hi Clint
Just another thing, you may want to check the distributor, if the advance system is not operating (may be seized up or something ) them you motor will be running to far retarded at the higher R.P.M. and this will also rase the temperature

similar problem. getting to use a neighbors boat. 2001 2300sb with the 350 efi, f/w cooled with the bravo 3.
when i first got ahold of her, he did ZERO maintenance.
the outdrive was plugged. starter bad, needed a tune up. manifolds cracked.
so i cleared the outdrive, replaced the impeller, cleaned the exchanger, replaced manifolds, risers, and elbows. full tune up, oil change, filters, ignition module in distrubutor, and coil(cracked tower).
engine runs great, however once i do anything other than troll, the overheating alarm goes off and temp gauge shows 210+
so i checked all seawater hoses, disconnected them and started the motor step by step, plenty of flow.
i installed at calibrated mechanical gauge in the engine compartment(sender in the intake manifold)... it is showing 40degrees cooler than the dash gauge.

question. 20mph cruise she runs 170-190*. 30mph gets to 195-200*. 40 mph blasts gets to 205* and stays there. if you guys are experiencing 170* temps, why is mine higher? and at 205* i actually am not worried, but curious as to the difference.

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!